Field of the Invention
The present invention relates generally to catheter systems, and more specifically to ultrasound control and/or catheter systems.
Description of the Related Art
Ultrasonic energy had been used to enhance the intravascular delivery and/or effect of various therapeutic compounds. In one system, ultrasound catheters are used to deliver ultrasonic energy and therapeutic compounds to a treatment site within a patient's vasculature. Such ultrasound catheters can comprise an elongate member configured to be advanced through a patient's vasculature and an ultrasound assembly that is positioned near a distal end portion of the elongate member. The ultrasound assembly is configured to emit ultrasonic energy. Such ultrasound catheters can include a fluid delivery lumen that is used to deliver the therapeutic compound to the treatment site. In this manner, ultrasonic energy is delivered to the treatment site to enhance the effect and/or delivery of the therapeutic compound.
For example, ultrasound catheters have been successfully used to treat human blood vessels that have become occluded by plaque, thrombi, emboli or other substances that reduce the blood carrying capacity of the vessel. See, for example, U.S. Pat. No. 6,001,069. To remove the occlusion, the ultrasound catheter is advanced through the patient's vasculature to deliver a therapeutic compound containing dissolution compounds directly to the occlusion. To enhance the effect and/or delivery of the therapeutic compound, ultrasonic energy is emitted into the therapeutic compound and/or the surrounding tissue at the treatment site. In other applications, ultrasound catheters are used for other purposes, such as for the delivery and activation of light activated drugs. See, for example, U.S. Pat. No. 6,176,842.
Pulmonary embolisms (PE) are caused when a large blood clot obstructs the major blood vessels leading from the heart to the lungs. The victim's heart can be suddenly overwhelmed with the task of pushing blood past this obstruction. About 5% of PE's are classified as massive and can result in rapid heart failure, shock and death without immediate therapy. Such massive PE's have traditionally been treated by a large dose of clot-dissolving drug (i.e., a thrombolytic). However, such treatment can result in unintended bleeding and even fatalities. Up to 40% of PE's are less critical obstructions, often called sub-massive PE. Current treatment protocols include treatment with anti-coagulant medication. Such treatments do not remove the clot but simply prevent the clot from growing larger. Recent studies suggest that failure to remove these sub-massive clots may have long-term adverse consequences including recurrent PE, chronic pulmonary hypertension and death. In U.S. Patent Publication No. 2012/0289889, Applicant discloses an ultrasound catheter system that is particularly useful in delivering a therapeutic compound and/or ultrasound energy to a treatment site to treat pulmonary embolisms. While the system described in U.S. Patent Publication No. 2012/0289889 is useful, there is a general desire to continue to improve the operability and ease of use of such system.